Embodiments in accordance with the present invention relate to data storage devices and disk drives and, more particularly, to a load/unload mechanism thereof.
The devices using an optical disk, a magnetic tape, or other forms of media are known as data storage devices. Among them, a hard disk drive (HDD) is commonly used as a storage device for a computer, and the HDD is one of storage devices essential for computer systems which are currently used. In addition, the use of the HDD are not only limited to computer systems but also has widely expanded because of the superior characteristics. The HDDs are used, for example, for moving picture recording/reproducing devices, car navigation systems, cellular phones, removable memories used for digital cameras and the like.
The HDD includes a magnetic disk in which data is recorded, and a head that writes data to and/or reads data from the magnetic disk. The head includes a head element and a slider. The head element is a thin film element. The slider has the head element disposed on a surface thereof. Further, the head element includes a write element portion and a read element portion. The write element portion converts an electric signal to a magnetic field according to data to be recorded in the magnetic disk. The read element portion converts a magnetic field from the magnetic disk to an electric signal.
The HDD further includes an actuator that moves the head to any desired position on the magnetic disk. The actuator driven by a voice coil motor (VCM) pivots with a rotating shaft used as an central axis of the pivot movement, thus actuating the head to move above a rotating magnetic disk in a radial direction of the magnetic disk. The movement of the head slider allows the head (head element) to access a desired track formed on the magnetic disk to perform data read/write operations.
In addition, a load/unload type HDD includes a ramp that has a retracted position onto which the head is retracted from the surface of the magnetic disk. The ramp is disposed in proximity to an outer peripheral end portion of the magnetic disk. As the rotation of the magnetic disk stops, the head is attracted to the surface of the magnetic disk. Accordingly, when the rotation of the magnetic disk stops, the actuator retracts the head from a recording surface of the magnetic disk to the ramp.
The actuator includes a suspension for supporting the head and an arm. The suspension includes a tab disposed at a leading end thereof. As the tab is guided into the ramp, the head is retracted to the outside of the magnetic disk from a position above the surface of the magnetic disk to be unloaded. As the tab leaves the ramp, on the other hand, the head is moved inward to the point above the surface of the magnetic disk from the outside of the magnetic disk to be loaded.
FIG. 9 is a side elevational view showing a load beam 910 disposed at a leading end portion of a suspension used in a conventional HDD. FIG. 9 shows a state of the load beam 910 when a head 905 is located above a magnetic disk 901.
Referring to FIG. 9, the head 905 is supported at a single point by a dimple 960 disposed on the load beam 910. The head 905 thereby flies at a predetermined height above the surface of the magnetic disk 901. A tab 916 extends from a leading end portion of the load beam 910 and is bent in the direction away from the magnetic disk 901. Specifically, the tab 916 is formed to be higher than a head support portion 961 of the load beam 910 above the magnetic disk 901. Especially, the tab 916 extends in the direction identical to the direction in which the load beam 910 (the head support portion 961) extends. Specifically, in the state where the head 905 flies above the magnetic disk 901, the load beam 910 (the head support portion 961) is inclined at substantially the same angle as the one at which the tab 916 is inclined relative to the surface of the magnetic disk 901.
FIG. 10 is a view showing the state during loading or unloading as viewed from the side of a leading end of the conventional load beam 910. FIGS. 11(a) to 11(c) are views showing the states during loading or unloading as viewed from the side of the conventional load beam 910.
Referring to FIG. 10, sliding the tab 916 along a sliding surface 800 that is a front surface of a ramp 915 during unloading makes it possible to lift the load beam 910 up to a predetermined height, thereby to cause the head 905 to moves away from the magnetic disk 901. During the time, the tab 916 first slides along, while being in contact with, a magnetic disk side inclined surface 801 of the sliding surface 800 to be eventually lifted up to a maximum lift surface 802. In FIG. 10, reference numeral 901a represents a position of the tab 916 to make the first contact with the magnetic disk side inclined surface 801. Reference numeral 901b represents a position of the tab 916 to be lifted up to a height required to position the head 905 away from the magnetic disk 901. Further, a height H represents a distance required to position the head 905 away from the magnetic disk 901.
Referring to FIG. 11(a), during loading or unloading, a corner 915a that is the sliding surface of the ramp 915 on the side of the tab 916 contacts part of an abdominal surface 916a of the tab 916, and a leading end portion 916a of the tab 916 is away from the sliding surface 800 of the ramp 915. The position and size of the ramp 915 vary according to mechanical errors. Herein, only errors in a ramp assembly position (in the direction toward a rotary shaft of the suspension) are considered without considering errors in the height direction of the ramp. For example, the errors in the ramp assembly position include an actuator assembly error and a ramp assembly error.
FIG. 11(a) is a view showing the state where there is no error in the assembly position of the ramp 915. FIG. 11(b) is a view showing the state where a side surface 915b of the ramp 915 on the side of the load beam 910 is far away from the load beam 910. FIG. 11(c) is a view showing the state where the side surface 915b of the ramp 915 on the side of the load beam 910 is close to the load beam 910.
In the state shown in FIG. 11(a), the corner 915a of the ramp 915 is in contact with a point near the center of the abdominal surface 916a of the tab 916. In the state shown in FIG. 11(b), since the side surface 915b of the ramp 915 is far away from the load beam 910, the corner 915a of the ramp 915 is in contact with a leading end side of the abdominal surface 916a of the tab 916. In the state shown in FIG. 11(c), since the side surface 915b of the ramp 915 is close to the load beam 910, the corner 915a of the ramp 915 is in contact with the root side of the abdominal surface 916a of the tab 916. Specifically, the corner 915a represents a point of contact between the ramp 915 and the tab 916, and the point of contact between the ramp 915 and the tab 916 varies due to the error in the assembly position of the ramp 915. Accordingly, the error in the assembly position of the ramp 915 should be taken into consideration and the tab 916 should be adapted to have a length long enough to reach the ramp 915 even when the ramp 915 is disposed to be farthest away from the load beam 910.
Further, considering an inclination of the load beam 910 relative to the magnetic disk 901 when the load beam 910 is lifted up, it is assumed that the inclination of the load beam 910 in the state shown in FIG. 11(a) is q1, the inclination of the load beam 910 in the state shown in FIG. 11(b) is q2, and the inclination of the load beam 910 in the state shown in FIG. 11(c) is q3. Then, since the position at which the tab 916 is contact with the ramp 915, that is, the position at which the tab 916 is lifted up are different from each other, the relationship of q2<q1<q3 are established.
If the inclination of the load beam 910 during loading or unloading varies due to the error in the assembly position of the ramp 915, the position (901b shown in FIG. 10) at which the head 905 is moved away from the magnetic disk 901 during unloading varies. For example, if the inclination of the load beam 910 is small because of the corner 915a of the ramp 915 being disposed far away from the load beam 910 as shown in FIG. 11 (b), the position at which the head 905 is moved away from the magnetic disk 901 during unloading is far away from the center of the magnetic disk 901. If the inclination of the load beam 910 is large because of the corner 915a of the ramp 915 being disposed close to the load beam 910 as shown in FIG. 11(c), the position at which the head 905 is moved away from the magnetic disk 901 during unloading is close to the center of the magnetic disk 901.
The position 901b, at which the head 905 is moved away from the magnetic disk 901, determines the range of a recording area on the magnetic disk 901. If the position 901b is changed by the error in the assembly position of the ramp 915, the recording area on the magnetic disk 901 also changes. It is therefore necessary to take into consideration the error in the assembly position of the ramp and thereby define, as an effective recording area, a narrow range of recording area in the state where the ramp is disposed the closest to the load beam. The ramp is required to be high enough to secure a disk recording area while the load beam is lifted up to a required height regardless of the error in the assembly position of the ramp. If the ramp is high, however, it imposes restrictions on the thickness of the magnetic disk drive.
Further, the error in the assembly position of the ramp varies the length from the point of contact between the tab and the ramp to the leading end of the tab. As a result, the height up to the leading end of the tab is not constant when the tab is in contact with the ramp. Consequently, the restrictions are imposed on the thickness of the magnetic disk drive, since it is also necessary to consider the case where of the root side of the tab can be in contact with the ramp, as shown in FIG. 11(c).
Patent Document 1 (Japanese Patent Laid-open No. 2005-71588) discloses an arrangement in which a tab includes a protrusion that is disposed at a leading end thereof and in contact with a ramp in order to reduce an area of contact between the tab and the ramp. The protrusion is not, however, intended to expand the storage capacity of the magnetic disk or make the magnetic disk drive thinner. In addition, the tab as disclosed in Patent Document 1 is extended in a flat sheet shape from the leading end of the load beam. As a result, the tab tends to flexible when the protrusion of the tab contacts the ramp, posing a problem of inferior rigidity of the tab.
Further, referring to FIG. 10, the conventional tab 916 has a width narrower than the head support portion 961 of the load beam 910. The tab 916 is extended from the center of the leading end of the load beam 910, having a U-shaped cross section in a crosswise direction (the same applies to the arrangement disclosed in Patent Document 2 (Japanese Patent Laid-open No. 2005-11511). Accordingly, during unloading, the magnetic disk side inclined surface 801 of the ramp 915 contacts the center of the tab 916, that is, the center of the load beam 910.
Depending on the position and shape of the ramp, for example, there may be cases where the head 905 is preferably positioned closer to the center of the magnetic disk when the tab 916 makes the first contact with the ramp 915 during unloading, or where the point of contact 901a between the tab 916 and the ramp 915 is preferably positioned at a point closer to the outside of the magnetic disk. In these cases, the conventional arrangement has the tab 916 disposed asymmetrically relative to the center of the load beam 910 in the crosswise direction. According to the arrangement disclosed in Patent Document 3 (Japanese Patent Laid-open No. Hei 11-250603), the portion of contact between the tab and the ramp is inclined relative to a central axis of the suspension. The tab formed asymmetrically or the portion of contact between the tab and the ramp being inclined leads to severe vibration during loading or unloading because of a torsional stress involved, or dynamic characteristics of the suspension including the load beam could be substantially aggravated.
It is to be noted that, in the arrangement disclosed in Patent Document 4 (Japanese Patent Laid-open No. Hei 8-221922), the suspension has a symmetrical leading end and includes a flange portion formed at part of an outer periphery of the leading end thereof. This flange portion is made to be in contact with the ramp (a lift portion). Since the flange is disposed only at a position of the suspension in contact with the ramp in this case, vibration caused by a torsional stress cannot be prevented during loading or unloading.
As described heretofore, the conventional HDD includes the tab that is extended in the same direction as the head support portion of the load beam and the abdominal surface of the tab contacts the corner of the ramp during loading or unloading. Accordingly, the length of the tab and the recording area of the magnetic disk are subject to restrictions imposed by the error in the assembly position of the ramp. There is therefore the problem in that it is difficult to increase the storage capacity of the magnetic disk and make the magnetic disk drive thinner.
Further, the conventional HDD has the arrangements in which the tab is disposed asymmetrically, the portion of the tab in contact with the ramp is inclined, or the tab includes the flange formed at only the portion in contact with the ramp, when the point of the first contact between the tab and the ramp during unloading is positioned closer to the outside of the disk. This poses the problem of decreasing rigidity of the tab and dynamic characteristics of the suspension.